1. Field of the Invention
The present invention relates to a catalytic process for producing substituted ketones by reacting an organic halide with a ketone in the presence of alkali metal hydroxide and a catalyst, the reaction proceeding via intermolecular liberation of hydrogen chloride.
More specifically, the instant invention relates to a process for preparing substituted ketones by reacting an organic halide with a ketone having one or more replaceable active hydrogen atoms on either or both of the carbon atoms alpha to the carbonyl group in the presence of an alkali metal hydroxide and certain catalytic phosphonium salts.
2. Description of the Prior Art
It is well-known in the prior art that substituted ketones may be prepared by reacting an organic halide with a ketone having replaceable active hydrogen atoms on the carbon atoms adjacent to the carbonyl group in the presence of alkali metal hydroxide and a catalyst, and the reaction mechanism is typically represented as follows: ##STR1## WHERE M is an alkali metal.
For instance, according to the specification of U.S. Pat. No. 2,644,843, allyl methyl ketone reacts with alkyl halide in the presence of alkali-metal hydroxide.
Further, British Pat. No. 851,658 discloses that 6-methyl-4-heptene-2-one (hereinafter, referred to as "methyl heptenone") is produced by reacting 1-chloro-3-methyl-2-butene (hereinafter, abbreviated to "prenyl chloride") with acetone.
However, by the method described in the specification of the foregoing British Patent the yields obtained are 43% using potassium hydroxide, and as little as 20% with sodium hydroxide.
In the latest issue of the "Yuki Gosei-Kagaku (Journal of Organic Synthetic Chemistry, Japan)" 28, 54 (1970), experimental results obtained according to the method of the abovementioned British Patent indicate that the yields of substituted ketone were 35% using potassium hydroxide and less than 5% using sodium hydroxide, and that the yield was increasing by the addition of dimethyl formamide or dimethyl sulfoxide to the reaction system.
U.S. Pat. No. 3,668,225 also discloses the attainment of enhanced yields by the addition of amine compounds of various types.
According to the reaction set forth above, water is an inevitable reaction product and it is substantially impossible to carry out the reaction under absolutely anhydrous conditions.
It has heretofore been generally believed that the addition of considerable amounts of water to the reaction system at the beginning of the reaction should be avoided since presence of large amounts of water in the system considerably decreases the reaction yield. Conventionally, the amount of water in the system has been minimized by restricting the water content of the reactants and alkali metal hydroxide was added in solid form to the reaction system.
For example, it is stated in Japanese Pat. No. 40 (1965) 22,251, which corresponds to U.S. Pat. No. 3,668,255 that the dryness of the reactants is not critical when the reaction is effectuated in the presence of an aminecatalyst, and in most cases the reaction proceeds without impairment in the presence of not more than 2 moles of water per 1 mole of organic halide. However, it should be noted that in all the examples of said patents, the reactions were initiated under substantially anhydrous conditions.
According to the results of experiments performed by the present inventors, the reaction of prenyl chloride with acetone in the presence of alkali metal hydroxide was significantly inhibited by a very small amount of water present in the acetone, and further the yields of the reaction were definitely decreased by adding substances such as potassium iodide, sodium iodide, dimethyl sulfone, sulfolane, tri-n-butyl phosphine oxide, monomethyl amine, dimethyl amine, trimethyl amine, monoethyl amine, monocyclohexyl amine, ammonium chloride due to the presence of water in these reactants. Taking into account that a considerable amount of manufacturing cost is to be saved by omitting rigorous drying of the reacting materials, it is evident that this reduction in costs cannot be realized using conventional processing in which the permissible amount of water present in the reaction system must be limited to not more than 2 moles of water per 1 mole of organic halide.